With the development of the technology of touch screen, different touch technologies have been developed. The touch technologies mainly include the following types in terms of the operating principle thereof: a resistive touch screen, a capacitive touch screen, an infrared touch screen, an electromagnetic touch screen, and a surface acoustic wave touch screen, wherein, the capacitive touch screen has been employed most widely. Capacitive touch screens include a self capacitance touch screen and a mutual capacitance touch screen. As compared to the self capacitance touch screen, the mutual capacitance touch screen has become the mainstream of the existing touch screens for its advantages of high anti-interference performance, high sensitivity, multi-touch, high recognition performance, and the like.
Depending on an integration mode of a touch screen with a display screen in a display device, touch screens mainly include a out-cell touch screen (wherein, for example, a touch screen is attached to a display screen), a on-cell touch screen in which a touch sensor is provided on a liquid crystal panel (i.e., wherein a touch screen is arranged between a color-filter substrate and a polarizer of a display screen), and a in-cell touch screen in which a touch sensor is provided inside a liquid crystal panel (i.e., wherein the function of a touch panel is embedded into a liquid crystal pixel).
With the increasing requirement for a lighter and thinner touch screen in the market, it will become an inevitable trend that a two-layer glass (Sensor Glass+Cover Glass) touch screen is replaced by a one glass solution (OGS) capacitive touch screen. OGS means a single-piece-of-glass solution, and means that a touch layer of a touch screen is formed on a single glass substrate. Wherein, the single glass substrate serves as both a touch substrate and a protection substrate. Whereas, the two-layer glass touch screen uses two pieces of glass, one of which serves is used as a touch substrate on which a touch layer is formed, and the other serves is used as a protection substrate; the protection substrate and the touch substrate are aligned and assembled to protect the touch layer. As compared to the two-layer glass touch screen, the one glass solution capacitive touch screen saves one glass substrate, thus also saves a process for attaching the omitted glass substrate during manufacturing the touch screen, thus the touch screen can be formed thinner with lower cost. Hence, The OGS has become the current mainstream of touch screen technology.
The one glass solution capacitive touch screen is a mutual capacitance touch screen, and its basic operating principle is as follows. There are provided two adjacent conductors and an inherent capacitance therebetween. When another conductor (e.g., a finger) comes close to the two conductors, inductive capacitance will be generated between the another conductor and the two conductors. The inductive capacitance will be connected to the inherent capacitance in parallel, causing the overall capacitance to increase. The overall capacitance will be restored to the inherent capacitance after the finger is removed. The periphery of the touch screen is provided with a drive-control circuit, which detects a change of capacitance with and withouth a finger, so as to determine whether a touch on the touch screen occurs and determine a touch position. Thus, the touch function of the touch screen is completed.
The two conductors generating mutual capacitance in the one glass solution capacitive touch screen are a plurality of driving electrode chains arranged in an X direction of and a plurality of sensing electrode chains arranged in a Y direction, the X direction of being perpendicular to the Y direction. Each of the driving electrode chains and each of the sensing electrode chains are electrically connected to respective drive-control circuits, respectively. The driving electrode chains and the sensing electrode chains cross with each other in spatial positions, and form mutual capacitance (coupling capacitance). When there is a touch by a finger, the mutual capacitance changes. The change of the mutual capacitance is detected by a drive-control circuit, so that the specific touch position is determined.
In a traditional one glass solution capacitive touch screen, both the driving electrode chains and the sensing electrode chains are made of an indium tin oxide (ITO) film. The ITO film is a transparent conductor, which facilitates normal touch on the touch screen while keeping normal display of a display screen. However, since the driving electrode chains and the sensing electrode chains almost cover the whole touch region of the touch screen and the indium tin oxide film has very large surface resistance, the touch screen has very high power consumption. Thus, the indium tin oxide film is not suitable for touch and control of a large-size screen. In addition, since the indium tin oxide film is used as transparent electrodes of most display devices, resources thereof are relatively short and the price thereof is increased with time goes on, which is not helpful to reduce the manufacturing cost of a touch screen or even a display screen.